The Boyz Doc: Dr Laura Waters on the International AIDS Society Conference in Paris

The International AIDS Society (IAS) conference is held every two years and brings together clinicians, researchers, policy makers, advocates and community organisations from all over the globe. The conference included hundreds of oral and poster presentations on a huge range of topics but prevention dominated and I will focus on research related to pre-exposure prophylaxis (PrEP).

For anyone unfamiliar, PrEP is when an HIV-negative person takes HIV drugs before sex to reduce their risk of getting HIV. Several studies have shown PrEP works if taken regularly and two big studies published in 2015 showed the HIV drug Truvada (a pill containing 2 HIV drugs) was very effective in gay men whether taken every day (PROUD trial) or for a short period before/after sex which is also called ‘event-based PrEP’ (IPERGAY trial) – both studies showed men who took PrEP were almost 90% less likely to get HIV than those who did not. PrEP is available in Scotland and Wales; it’s not yet available in England but a large trial providing PrEP to up to 10,000 people should start in September at sexual health clinics across the country.

What was new in Paris?

In IPERGAY, event-based PrEP meant taking two Truvada tablets 2-24 hours before sex and then one tablet every 24 hours until 2 doses after the last episode of condomless sex (it’s clearer with pictures, which are accessible here http://i-base.info/guides/prep). The published study showed 86% less new HIV in men on PrEP and longer follow-up showed 97% less new HIV than expected in men taking PrEP!

However, in IPERGAY men took an average of 4 tablets a week; taking Truvada this often means high levels of drug in the body most of the time – would event-based PrEP be so effective if taken less often? To address this the IPERGAY team analysed only the men who took fewer than 15 tablets a month (the average was 9.5 tablets covering 5 episodes of sex a month) and confirmed PrEP was still highly effective with no infections in the men taking active PrEP. So, event-based PrEP is effective in people taking it less often. The effectiveness of this pattern of PrEP has only been proven in men who have sex with men.

Amongst people who buy PrEP online in England, estimates suggest only around 1 in 10 use event-based PrEP with most preferring to take it every day. Why men choose daily rather than ‘on demand’ PrEP was explored in interviews with people accessing PrEP in a study in Amsterdam. At the beginning most chose daily PrEP plus during the study more people moved from event-based to daily. At the start of the study the main reasons for choosing to take PrEP every day were: wanting a routine, concern about remembering to take non-daily PrEP and having frequent sex; reasons for choosing event-based PrEP were: reporting they usually planned their sex, having risky sex only occasionally and concern about side-effects. Looking at men who changed from event-based to daily PrEP the main reasons included: realising sex was not as predictable as they’d thought and having more frequent sex. This study shows that it’s important to have a choice that fits people’s sexual lifestyles and preferences.

Staying in France, the first European country to approve PrEP, they are planning another study to get 3,000 people in PrEP to see if they can show a drop in new HIV infections at a city level we have good evidence for PrEP on an individual level we are lacking clear data to support a public health benefit and in Paris the annual number of new HIV cases has not dropped. Although PrEP very likely played a role in the reported drop in new HIV cases in gay men in England last year we don’t have precise figures to prove that. The French study will also explore how to ensure migrants and other at-risk groups can access PrEP; current figures show that gay men account for 98% of PrEP use.

Back to the PROUD study new results continue to show a much lower rate of new HIV infections in men using PrEP. PROUD researchers also performed interviews in some participants and demonstrated that men using PrEP don’t abandon other risk reduction strategies such as condoms, position choice and serosorting (choosing partners of the same HIV status) rather PrEP “loosened the boundaries” around their sexual choices. Some men described benefit in terms of fear or anxiety around sex, some calling PrEP a ‘safety net’.

Finally there was research presented on non-Truvada PrEP. Injectable drugs are an appealing alternative to pill-taking: a drug called cabotegravir reaches good levels when given by injection and will be studied further but another drug called rilpivirine didn’t and will no longer be explored as PrEP. Giving PrEP via a vaginal ring to women also looks promising.

More important data was presented to support the undetectable = uninfectious (U=U) message. The Terrence Higgins Trust have done a great job of promoting “Can’t Pass It On” now there’s clear evidence that HIV-positive people with an undetectable virus on treatment do not transmit to their sexual partners. At IAS more data was presented to support this. If your sexual partner is HIV-positive but undetectable on treatment you cannot acquire HIV and you do not need PrEP unless you have other partners who don’t know their HIV status or who have detectable virus.

Dr Laura Waters is an HIV and sexual health consultant at the Mortimer Market clinic and the Boyz Doc. Dr Laura answers your questions and reports on sexual health every two weeks in Boyz. If you have a question for Dr Laura please email her at boyzdoc@boyz.co.uk.